bool LocalEpoch::EnterEpoch(const uint64_t epoch_id) {
epoch_lock_.Lock();
// if this thread is never used or GC'd
if (epoch_lower_bound_ == UINT64_MAX) {
epoch_lower_bound_ = epoch_id - 1;
} else if (epoch_lower_bound_ >= epoch_id) {
// epoch_lower_bound_ has already been updated by the GC.
// have to grab a newer epoch_id.
epoch_lock_.Unlock();
return false;
}
auto epoch_map_itr = epoch_map_.find(epoch_id);
// check whether the corresponding epoch exists.
if (epoch_map_itr == epoch_map_.end()) {
std::shared_ptr<Epoch> epoch_ptr(new Epoch(epoch_id, 1));
epoch_queue_.push(epoch_ptr);
epoch_map_[epoch_id] = epoch_ptr;
} else {
epoch_map_itr->second->txn_count_++;
}
epoch_lock_.Unlock();
return true;
}
bool LocalEpoch::EnterEpoch(const eid_t epoch_id, const TimestampType ts_type) {
epoch_lock_.Lock();
// if this thread is never used or has been GC'd
if (epoch_id_lower_bound_ == UINT64_MAX) {
epoch_id_lower_bound_ = epoch_id - 1;
} else if (epoch_id_lower_bound_ >= epoch_id) {
if (ts_type == TimestampType::SNAPSHOT_READ) {
epoch_id_lower_bound_ = epoch_id - 1;
} else {
// epoch_id_lower_bound_ has already been updated by the GC.
// have to grab a newer epoch_id.
epoch_lock_.Unlock();
return false;
}
}
if (ts_type != TimestampType::COMMIT) {
auto epoch_map_itr = epoch_map_.find(epoch_id);
// check whether the corresponding epoch exists.
if (epoch_map_itr == epoch_map_.end()) {
std::shared_ptr<Epoch> epoch_ptr(new Epoch(epoch_id, 1));
epoch_queue_.push(epoch_ptr);
epoch_map_[epoch_id] = epoch_ptr;
} else {
epoch_map_itr->second->txn_count_++;
}
}
epoch_lock_.Unlock();
return true;
}
// the input parameter is the global read-only epoch id.
void LocalEpoch::EnterEpochRO(const uint64_t epoch_id) {
epoch_lock_.Lock();
// if this thread is never used or GC'd
if (epoch_lower_bound_ == UINT64_MAX) {
epoch_lower_bound_ = epoch_id - 1;
} else if (epoch_lower_bound_ >= epoch_id) {
epoch_lower_bound_ = epoch_id - 1;
}
if (epoch_map_.find(epoch_id) == epoch_map_.end()) {
std::shared_ptr<Epoch> epoch_ptr(new Epoch(epoch_id, 1));
epoch_queue_.push(epoch_ptr);
epoch_map_[epoch_id] = epoch_ptr;
} else {
epoch_map_.at(epoch_id)->txn_count_++;
}
epoch_lock_.Unlock();
}